Entities can't attack the player when they are falling

I know that you have to use external tool to do this, but it will be really bad for map makers.
So, i was playing around with mob and leash, and I created this (see image).
and to my great regret, mobs don't attack me.
When they are hang with a leash, mobs are consider as falling, and it happens the same thing when a mob is falling in a cobweb